The present invention relates to direct drive blood defibrination apparatus and methods.
There are a wide range of medical research and clinical laboratory applications for defibrinated blood, including the production of blood agar plates, the isolation of human T lymphocytes using the Rosette assay, and minimum inhibitory concentration studies. Quality assurance standards of the ovine blood product require a relatively high hematocrit, on the order of at least 35%, and the complete absence of fibrin and bacteria. In a known ovine blood collection and defibrination technique, a magnetic stirrer used to indirectly drive a stir bar is used. Such indirectly driven stir bar defibrination units have proven unreliable since the stir bar can jump out of the magnetic field or even stop as a result of blood turbulence during collection, inconsistent vacuum within the collection chamber, or uneven fibrin clot formation around the stir bar. When the stir bar stops, a web of fiber immediately forms entrapping erythrocytes in the fibrin clot resulting in an undesirable increase in the size of the fibrin clot and a resultant reduction in the volume of defibrinated blood product. In addition, indirectly driven defibrination units tend to reduce blood hematocrit and often do not sufficiently remove blood fibrin.
Due to the unreliable and unpredictable nature of such indirectly driven defibrination units, excess blood must be drawn in order to insure production of a desired volume of acceptably defibrinated blood. Also, since hematocrit is adversely affected, more donor candidates must be screened. This results in an increased herd size, increased collection time and potential monetary loss from excess blood which cannot be used.